Finally got to a point where I feel happy with my Fire, Earth, and basic Magic Damage builds. Fire Resist Earth Resist Magic Damage
Magic Damage I stack HP where I don't have a decent amount of Magic Damage Taken or Magic Defense Bonus, sometimes using Lamia Mantle +1, sometime using Cassie/Intruder Earring, sometimes not swapping Main/Sub if I'm about to Chivalry or Spirits, it's situational.
Obvious upgrades that I'm striving for as I have the cash:
Numinous Shield +1
Coral Scale Mail +1 (Friend just hit 100 Bonecraft, gonna try for this soon)
Assault Breastplate (I do Unvinvited Guests almost every week)
Sand Gloves (0/5, I hate Nussnacker)
Tarasque Mitts +1
Cerberus Mantle (This is top priority at the moment)
I'm insanely happy with it so far, the difference is extremely noticeable.
Couple pics of Bahamut V1, I had Barfira from a meritted WHM with AF2 legs and Fire Carol with a Crumhorn+1 0 was with Rampart up, 93 was the norm.
And my damage taken versus normal damage from this BC